1. Field of the Invention
The present invention relates to image processing for displaying an indication indicating the position of an object detected from an image such that the indication is superimposed on the image.
2. Description of the Related Art
In recent years, digital cameras are capable of detecting the position and size of a particular object, such as the face of a human being, in an image in accordance with an image recognition algorithm have been developed. A technique for performing automatic focus control and exposure control by increasing the weighting on an evaluation value obtained from an area containing a particular object is disclosed, for example, in Japanese Patent Laid-Open No. 2006-145629.
In this case, information indicating the position of the particular object (for example, a frame enclosing the face of a human being) is displayed so as to be superimposed on a display image displayed on a display unit, such as a liquid crystal display (LCD), provided on the back side of a digital camera. The information indicating the position of the particular object is added to an image signal to be displayed on the display unit and is not added to an image signal of a static image to be recorded in a recording medium.
Video cameras having an electronic image-stabilization function of detecting, in accordance with an output of an acceleration sensor or a motion vector component obtained by image processing, an image shake component generated in a shooting operation and performing correction processing for canceling out the detected image shake component are available. More specifically, as disclosed in Japanese Patent Laid-Open No. 2002-148670, an image output from an image pickup element is temporarily recorded in a frame memory, a cut-out position is set so as to compensate for an image shake component, and cut-out processing is performed on the image in accordance with the set cut-out position.
For cameras not provided with such an electronic image-stabilizer, in a case where a cut-out position is not designated, the center position of the field angle of a display image displayed on a display unit often corresponds to the center position of the field angle of an image output from an image pickup element. However, for video cameras provided with such an electronic image-stabilization function, due to an operation of the electronic image-stabilization function, the center position of the field angle of a display image displayed on a display unit often does not correspond to the center position of the field angle of an image output from an image pickup element.
Under such circumstances, in order to apply a technique for detecting, in accordance with an image recognition algorithm, the position and size of a particular object, such as the face of a human being, in an image of a video camera provided with such an electronic image-stabilization function, it is important to take into account for a cut-out position.
In the case that a particular object is not a stationary body but a moving body, such as a human being or an animal, an increase in the time for detecting the position of the particular object causes a difference between the detected position and an actual position where the particular object is actually located. Thus, it is desirable to reduce the time required for obtaining a detection result of the position of the particular object as much as possible. In addition, it is necessary to start detection processing for the particular object as soon as possible once an image signal is obtained. To this end, it is desirable to detect the position of the particular object from an image that has not been subjected to electronic image-stabilization rather than from an image that has been subjected to electronic image-stabilization.
However, it is assumed that the position of the particular object that is located at the center of the field angle may be slightly shifted to the right of the field angle due to cut-out processing for the image being performed by the electronic image-stabilization. In this state, in the case that the position of the particular object is detected from an image that has not been subjected to electronic image-stabilization, the detected position of the particular object does not correspond to the position of the particular object in the displayed image that has been subjected to electronic image-stabilization.
That is, as a result of electronic image-stabilization, an indication indicating the detected position of an object may be displayed so as to be shifted from the position of the object in a displayed image that has been subjected to electronic image-stabilization.